NGC 6981 / C2050-127 / Messier 72 (Updated August 2014) RA: 20:53:27.70 DEC: -12:32:14.3 (J2000) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Units for position R0 denotes RA, DEC in the J2000 coordinates R5 denotes RA, DEC in the 1950 coordinates XA denotes X, Y in arcseconds XP denotes X, Y in pixels 37-44 F8.4 Period (days) 46-51 F6.3 Mean magnitude (or maximum magnitude if "max" is indicated in the remarks column) 53-57 F5.3 Light amplitude (range of variability) 59 A1 Colour for mean magnitude and amplitude e.g. B, V, R, I, J, K or P (for photographic). 61-65 A5 Type of variable (draft 2006 GCVS classifications) CST denotes non variable stars previously designated as variables 67-80 A19 Notes and Remarks (f denotes field star) "--" or "----" indicates no data available ========================================================================= ID Position Period ampl C Type Notes/ RA/X Dec/Y Units Remarks ========================================================================= 1 20:53:31.10 -12:33:11.7 R0 0.6198 16.87 0.62 V RR0 2 20:53:34.55 -12:29:02.5 R0 0.4653 16.87 1.20 V RR0 3 20:53:24.56 -12:33:17.4 R0 0.4976 16.79 0.88 V RR0 4 20:53:20.80 -12:31:42.7 R0 0.5525 16.89 0.91 V RR0 5 20:53:25.57 -12:32:41.4 R0 0.5073 16.74 0.96 V RR0 6 20:53:33.19 -12:30:57.7 R0 ---- -- -- CST 7 20:53:27.85 -12:31:19.3 R0 0.5247 16.84 0.87 V RR0 8 20:53:27.57 -12:30:47.8 R0 0.5684 16.88 0.81 V RR0 9 20:53:28.65 -12:31:28.2 R0 0.6029 16.88 0.64 V RR0 10 20:53:24.84 -12:33:31.3 R0 0.5582 16.89 0.90 V RR0 11 20:53:32.03 -12:32:51.3 R0 0.5207 16.87 0.82 V RR0 12 20:53:28.59 -12:32:38.7 R0 0.2879 16.72 0.47 V RR1 13 20:53:28.90 -12:32:02.2 R0 0.5420 16.56 0.86 V RR0 14 20:53:27.16 -12:31:42.8 R0 0.6072 16.76 0.65 V RR0 15 20:53:23.77 -12:32:39.0 R0 0.5405 16.87 0.85 V RR0 16 20:53:27.85 -12:32:37.0 R0 0.5752 16.79 0.77 V RR0 17 20:53:28.22 -12:33:00.0 R0 0.5735 16.86 0.84 V RR0 18 20:53:26.20 -12:32:54.5 R0 0.5356 16.62 0.83 V RR0 19 20:53:27.98 -12:30:23.5 R0 ---- -- -- CST 20 20:53:24.21 -12:32:03.8 R0 0.5950 16.88 0.71 V RR0 21 20:53:22.39 -12:32:05.8 R0 0.5312 16.92 1.07 V RR0 22 20:53:20.27 -12:32:18.4 R0 ---- -- -- CST 23 20:53:21.14 -12:30:22.1 R0 0.5851 16.91 0.67 V RR0 24 20:53:27.16 -12:32:42.0 R0 0.3271 16.42 0.29 V RR1 25 20:53:18.87 -12:31:13.8 R0 0.3534 16.80 0.42 V RR1 26 20:53:21.86 -12:33:04.4 R0 ---- -- -- CST 27 20:53:42.60 -12:36:06.8 R0 0.6739 16.62 1.11 V RR0 Note 28 20:53:32.22 -12:30:56.8 R0 0.5673 16.88 0.69 V RR0 29 20:53:25.77 -12:33:11.8 R0 0.5974 16.85 0.87 V RR0 30 20:53:32.99 -12:33:52.2 R0 ---- -- -- CST 31 20:53:28.18 -12:31:42.9 R0 0.5423 16.80 0.69 V RR0 32 20:53:18.82 -12:33:01.4 R0 0.5283 16.91 0.98 V RR0 33 20:53:28.18 -12:33:22.1 R0 ---- -- -- CST 34 20:53:27.57 -12:32:10.3 R0 ---- -- -- CST 35 20:53:43.55 -12:31:54.4 R0 0.5438 16.89 0.84 V RR0 36 20:53:27.03 -12:32:16.9 R0 0.5826 16.70 0.70 V RR0 37 20:53:28.66 -12:32:24.4 R0 ---- -- -- CST 38 20:53:28.45 -12:32:26.8 R0 ---- -- -- CST? 39 20:53:41.02 -12:28:16.1 R0 0.4268 17.30 0.46 V RR0 f 40 20:53:29.19 -12:32:01.6 R0 ---- -- -- CST 41 20:53:28.90 -12:32:38.9 R0 ---- -- -- CST 42 20:53:28.85 -12:32:16.8 R0 ---- 13.85 0.36 V SR? Note 43 20:53:27.36 -12:32:22.4 R0 0.2835 16.74 0.49 V RR1 44 20:53:28.02 -12:32:29.7 R0 0.5574 16.87 0.89 V RR0 45 20:53:28.66 -12:32:20.2 R0 0.3650 16.77 0.49 V RR1 46 20:53:28.97 -12:32:26.5 R0 0.2867 16.67 0.26 V RR1 47 20:53:29.73 -12:32:26.3 R0 0.6491 16.86 0.25 V RR0 48 20:53:26.46 -12:32:27.3 R0 0.6398 16.84 0.46 V RR0 49 20:53:28.27 -12:32:10.9 R0 0.5783 16.73 0.79 V RR0 50 20:53:28.25 -12:31:58.3 R0 0.4889 16.61 0.93 V RR0 51 20:53:28.41 -12:32:32.3 R0 0.5486 16.58 0.63 V RR0 52 20:53:27.96 -12:32:02.3 R0 0.6987 16.72 0.61 V RR0 53 20:53:27.00 -12:32:16.7 R0 0.6521 16.87 0.45 V RR0 54 20:53:28.66 -12:32:02.5 R0 0.0773 17.95 0.22 V SXPhe 55 20:53:24.45 -12:31:27.3 R0 0.0470 19.34 0.17 V SXPhe 56 20:53:28.93 -12:33:05.9 R0 0.0405 19.613 0.087 V SXPhe Note 57 20:53:27.38 -12:32:13.3 R0 0.3351 16.63 0.32 V RR1 58 20:53:27.12 -12:32:13.9 R0 0.285 -- -- ? Note 59 20:53:48.89 -12:36:44.8 R0 0.6033 16.86 0.66 V RR0 60 20:53:46.68 -12:27:33.0 R0 0.4821 16.94 1.25 V RR0 ======================================================================= Supplementary Notes The RA and dec are from the following sources: V1-42 (Samus et al. 2009), V43-56 (Bramich et al. 2011), V57-58 (Skottfelt et al. 2013b) and V59-60 (Amigo et al 2013). Most of the remaining data are from the study by Amigo et al. (2013) unless indicated otherwise in the Notes on individual stars. The "CST" classifications are from Bramich et al. (2011). Since Amigo et al. (2013) did not present any results for these stars, it is assumed they also did not detect any variability. ================================================ Notes on individual stars V42: Dickens & Flinn (1973) noted that this star was a red variable, but did not provide further data. Amigo et al. (2013) showed that it varies and that it lies near the red giant tip on the CM diagram. However, they were unsuccessful in deriving a period in the range expected for stars of this type. (Their best period was close to one day.) V56, V58: The data for these variables are from Bramich et al. (2011) and by Skottfelt et al. (2013), respectively. Their variability was at too low a level for Amigo et al. to obtain reliable results. ========================================================== Discovery of the variable stars in M72 V1-34 (V6, V19, V33 were supsected variables) discovered by Ritchie and announced by Shapley (1920) with x,y coordinates and an ID chart. Kadla et al. (1995) later showed that V6, V19 and V33 are giant branch stars. V35-41 Sawyer (1953) with x,y coordinates and an ID chart In the course of deriving the RA and dec for V14, V29, V33, V41, Samus et al. (2009) and Kadla et al. (1998) noted that there were errors in the published positions for these variables in earlier versions of our GC variable star catalogues. V42 Dickens & Flinn (1973) noted that they had discovered a new red variable near the cluster centre. The number 42 was assigned and x,y coordinates were listed by Sawyer Hogg (1973) in her 3rd catalog, based on unpublished correspondence with Dickens. V43-V49 = S3, S5, S7, S8, S9, R3, R4 Kadla et al. (1995, 1996) with x,y coordinates in arcsec and an ID chart in the 1996 paper. Approximately 33 of variables V1-42 were also labelled on the ID charts by Kadla et al. (1996). The numbers V43-49 were assigned by Bramich et al. (2011). In their papers, Kadla et al. listed 9 suspected variables (S1-9) and 7 possible RR Lyrae variables (R1-7), all based on their location in the CMD. They did not detect any variations because their study was based on one B frame and one V frame taken simultaneously. With their more extensive data set, Bramich et al. detected variation only in the seven listed here. The others are considered to be non-variable. V50-56 Bramich et al. (2011) with RA, dec and ID charts. They also published RA, dec and ID charts for the other variables they analysed in their study. V57-58 Skottfelt et al. (2013a) with RA, dec and an ID chart Skottfelt et al. (2013b) later pointed out that the coordinates for V57 and V58 had been switched in their original paper (2013a). The corrected coordinates are listed in the table above. V59-60 Amigo et al. (2013) with RA and dec (These two variables were outside the field of view of the study by Bramich et al. 2011). ------------------------------------------------------------------------- Lynch & Ransom (2011) conducted a search for pulsars, but did not find any in NGC 6981. ======================================================================== References Amigo, P., Stetson, P. B., Catelan, M., Zoccali, M., Smith, H. A. 2013, AJ, 146, 130 = arXiv:1308.6584 Bramich, D. M., Figuera, J. R., Giridhar, S., Arellano Ferro, A. 2011, MNRAS, 413, 1275 Cacciari, C., Corwin, T. M., Carney, B. W. 2005, AJ, 129, 267 Dickens, R. J. & Flinn, R. 1973, IAU Colloq 21, Var Stars in Globular Clusters and in Related Systems, 82 Kadla, Z. I., Brocato, E., Piersimoni, A., Gerashchenko, A. N., Malakhova, Y. N. 1995, A&A, 302, 723 Kadla, Z. I., Gerashchenko, A. N., Malakhova, Y. N. 1996, IBVS, 4413 Kadla, Z. I., Gerashchenko, A. N., Malakhova, Y. N. 1998, A&A Transactions, 15, 137 Lynch, R. S. & Ransom, S. M. 2011, ApJ, 730, L11 Rosino, L. 1953, Bologna Pub, 6, No. 2, 49 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sawyer, H. B. 1953, JRASC, 47, 229 Shapley, H. 1920, ApJ, 52, 73 Shapley, H. & Ritchie, M. 1920, ApJ, 52, 232 Skottfelt, J., Bramich, D. M., Figuera Jaimes, R., Jorgensen, U. G., Kains, N., Harpsoe, K. B. W., Liebig, C., Penny, M. T., Alsubai, K. A. and 27 coauthors, 2013a, A&A, 553, A111 Skottfelt, J., Bramich, D. M., Figuera Jaimes, R., Jorgensen, U. G., Kains, N., Harpsoe, K. B. W., Liebig, C., Penny, M. T., Alsubai, K. A. and 27 coauthors, 2013b, A&A, 558, C1. This paper published a Corrigendum for Skottfelt et al. (2013a) ========================================================================